Lighting macros

You can get a more interesting and natural looking lighting of your subjects by having a flash to the side along with the ambient light as a bare minimum setup or even better is to use two strobes with one putting out half as much light as the primary or key light strobe.

Nikon's SU-800 with the small SB-200 speedlight is a good combo for small subjects where the flash is small enough to position it where it will provide the best lighting.

I've done a great deal of experimenting with lots of different rigs, and the pop-up flash diffuser gives hands down the best, most natural looking light, and it's also the cheapest and simplest rig.

I have a Manfrotto twin macro bracket, and have used lots of different variations. They always create sharply defined highlights that don't look natural, and odd shadows.